Dr. Bill Elliott: No energy? Sleep apnea may be to blame.

Here's a quote from a leading TV health expert from a few years ago: "Are you tired, rundown, listless? Do you poop out at parties? Are you unpopular?" Of course our expert was Lucille Ball, and she was selling VitaMeataVegamen in a hilarious episode of "I Love Lucy" from 1952.

The writers of that episode knew that those of us who are "tired, rundown, listless" are a great target for snake oil because these are such common complaints. Everyone feels tired at times, but some of us really feel tired — even to the point of falling asleep during the day. Sometimes even while driving.

This sort of tiredness can be dangerous. But poor nutrition or lack of vitamins is not the culprit, the cause may be poor or disrupted sleep.

A group of experts just published an updated guideline on obstructive sleep apnea (OSA), a problem that is associated with an array of symptoms which include excessive daytime sleepiness, poor concentration, increased risk of motor vehicle accidents (as well as other accidents), and decreased quality of life. Studies show that up to 17 percent of the U.S. population may suffer from sleep apnea, with the prevalence higher in those over the age of 60.

OSA is caused by relaxation of the throat muscles during sleep. As the muscles relax, the airway closes down limiting the amount of air that can be inhaled with each breath. When breathing is restricted, the oxygen level in the blood drops, sending off "alarms" in the brain that leads to brief periods of semi-awakening and disrupted sleep. Many OSA sufferers snore loudly and may even make snorting or gasping sounds during sleep as they try to compensate for lack of oxygen.

The cycle of low oxygen and disruption in sleep can repeat itself throughout the night — from five to 30 times an hour — limiting restful and restorative sleep.

The "alarm" system caused by low oxygen levels may also trigger hormonal changes in the body associated with stress and "fight or flight" responses. This is one of the reasons that OSA is associated with a number of health risks including increased rates of cardiovascular disease, high blood pressure, impaired brain function, type 2 diabetes, and an increased risk of complications around surgical procedures.

The prevalence of OSA increases with age, but is it also found in younger adults and even adolescents, especially in those individuals who are overweight. As obesity rates grow in the country, the rate of OSA is also increasing.

The good news is that sleep apnea can be treated, but it needs to be diagnosed first. If you feel that you have excessive daytime sleepiness, especially if you snore and are overweight, you should talk to your health-care provider about a test for OSA. This generally involves an overnight test that can usually be done in your own bed at home, while you are monitored with portable equipment. Your doctor will likely also order blood tests to make sure there are no signs of thyroid problems or undiagnosed diabetes.

Once the overnight test is completed and the results are back, you might be a candidate for treatment of OSA — most commonly a device that you wear at night that helps keep the airway open during sleep. The machine delivers continuous positive airway pressure (CPAP) that keeps the muscles of the neck and throat from collapsing, blocking breathing.

For those who are candidates for CPAP or other treatments, the results can be life changing. Improving sleep quality and avoiding constant sleep interruptions often significantly improves daytime wakefulness and wellbeing. Other symptoms may improve as well including cognitive (brain) function. Results are mixed on whether CPAP helps reduce weight, but many OSA patients feel so much better with treatment that they are more energized to exercise and eat better.

Listen to Lucy. If you poop out at parties, you may have sleep apnea.

Dr. Bill Elliott is an internist at Kaiser Novato and an assistant clinical professor of medicine at UCSF. His column appears every third Monday.